Plasticized poly (vinyl chloride) (PVC) membranes containing aliphatic amines have been used to detect 2,4,6-trinitrotoluene (TNT) and other polynitroaromatics in water. Greatest stability has been achieved with Jeffamine T403, an amine that is highly compatible with PVC. The stability of these membranes to nitrogen loss has been evaluated in air and water as a function of the initial T403 Jeffamine concentration. The percentage loss of nitrogen with time decreases with decreasing initial amine concentration. Membranes that have been stored for 46 days in water still respond to TNT. Response to TNT is roughly proportional to nitrogen content in the membrane.